I am a big fan of the Timber plugin for theme development and Jetpack’s Photon for image manipulation and as a CDN.

Timber enables you to create clean WordPress templates using the popular Twig template engine. Photon automatically caches all the images in your posts and serves them from the WordPress servers, taking the load off of your own server.

I decided to put the two together in a plugin so that all other images in your Twig templates are sent through Photon as well. You can even use the image filters that come with Timber (resize, letterbox).